fix(junit): Replace spread operator with for-of loop to prevent RangeError with large console logs (#37767)

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: Skn0tt <[email protected]>
Co-authored-by: Simon Knott <[email protected]>

Author: Copilot

packages/playwright/src/reporters/junit.ts

@@ -193,8 +193,10 @@ class JUnitReporter implements ReporterV2 {
     const systemOut: string[] = [];
     const systemErr: string[] = [];
     for (const result of test.results) {
-      systemOut.push(...result.stdout.map(item => item.toString()));
-      systemErr.push(...result.stderr.map(item => item.toString()));
+      for (const item of result.stdout)
+        systemOut.push(item.toString());
+      for (const item of result.stderr)
+        systemErr.push(item.toString());
       for (const attachment of result.attachments) {
         if (!attachment.path)
           continue;

tests/playwright-test/reporter-junit.spec.ts

@@ -126,6 +126,28 @@ for (const useIntermediateMergeReport of [false, true] as const) {
       expect(result.exitCode).toBe(1);
     });
 
+    test('should handle large number of console logs', { annotation: { type: 'issue', description: 'https://github.com/microsoft/playwright/issues/37719' } }, async ({ runInlineTest }, testInfo) => {
+      test.slow();
+      // need to go via disk, otherwise our test harness would print 500k lines of stdout to the Github Actions UI that can't handle it.
+      const reportFile = testInfo.outputPath('report.xml');
+      const result = await runInlineTest({
+        'a.test.ts': `
+          import { test, expect } from '@playwright/test';
+          test('one', async ({}) => {
+            test.slow();
+            for (let i = 0; i < 500000; i++) {
+              console.log('log line ' + i);
+            }
+          });
+        `,
+      }, { reporter: 'junit' }, { PLAYWRIGHT_JUNIT_OUTPUT_FILE: reportFile });
+      expect(result.exitCode).toBe(0);
+      const report = await fs.promises.readFile(reportFile, 'utf8');
+      const testcase = parseXML(report)['testsuites']['testsuite'][0]['testcase'][0];
+      expect(testcase['system-out']).toHaveLength(1);
+      expect(testcase['system-out'][0]).toContain('log line 99999');
+    });
+
     test('should render stdout without ansi escapes', async ({ runInlineTest }) => {
       const result = await runInlineTest({
         'playwright.config.ts': `